Volume 10, Number 1
Feb 1986

Encapsulation Research

At a PLMS meeting at ALA Midwinter in Chicago, Merrily Smith
reported that the Library of Congress's Research and Testing Lab had
tested Mylar and polypropylene to find their effect on paper
encapsulated between sheets of these materials. Naturally they found
that the rate of deterioration was more rapid with higher
temperatures and paper pH. Deacidification slowed the rate of
deterioration, as night be expected.

Two other findings were much less predictable. The first
concerned the size of the gap commonly left in a corner of the
enclosure, to prevent the aging paper from "stewing in its own
juices," a matter of debate in conservation circles for years. They
found that the more of the edge was left open, the slower the paper
aged.

The second of these two findings confirmed the recommendation of
Tim Padfield, David Erhardt and Walter Hopwood, in their 1982 paper,
"Trouble in Store" (IIC Preprints):

Until a general purpose, wide range, showcase pollutant absorber
is developed we recommend, as an acid gas absorber,
carbonate-buffered paper, laid in cases. The exposed surface area of
absorber must be large.

At the Library of Congress, undeacidified paper that was
encapsulated together with a sheet of buffered paper behaved the
same as if it had been deacidified.